Refractory insert members, refractory block assembly including same and reformer flue gas tunnel assembly including same

ABSTRACT

A refractory block assembly for a steam reformer furnace tunnel includes a hollow main body, at least one first mechanical mating member defining a protruded portion extending from an upper surface of the main body, at least one second corresponding mechanical mating member defining an opening corresponding to the protruded portion formed in a portion of a lower surface of the main body, and at least one through-hole having openings formed in a first side and an opposed second side of the main body portion. A refractory insert member having mechanical mating features on at least a portion of the outer surface thereof resides within the at least one though-hole of the refractory block.

This application claims the benefit under 35 USC § 119(a)-(d) of U.S.Provisional Application No. 62/254,923 filed on Nov. 13, 2015, theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to refractory insert members forrefractory blocks and refractory block assemblies including those insertmembers, for use in connection with a refractory tunnel, also known as areformer flue gas tunnel, of a hydrogen reformer furnace, which is usedin steam methane reformer processes. More specifically, the presentinvention provides refractory insert members that are installed inrefractory blocks and which improve the structural stability of thetunnel walls or provide improved gas flow control. The refractory insertmembers and refractory block assemblies including those refractoryinsert members are preferably in connection with a light-weight,free-standing tunnel structure that is constructed without the use ofmortar, that better withstands the application of hydrogen reformers,and which includes refractory components having a more mechanicallyrobust design and made of higher performance material than that whichhas been used heretofore.

BACKGROUND OF THE INVENTION

A hydrogen reformer furnace converts natural gas into hydrogen through aseries of catalytic reactions. One of the most prevalent routes for theconversion of methane (CH₄) to petrochemicals is either through themanufacture of hydrogen, or a mixture of hydrogen and carbon monoxide.This hydrogen/carbon monoxide material is referred to as “Synthesis Gas”or “Syngas.” Indeed, steam methane reforming (SMR) of natural gas orsyngas is the most common method of producing commercial bulk hydrogenas well as hydrogen that is used in the industrial synthesis of ammonia.At temperatures around 1000° C., and in the presence of metal-basedcatalysts, steam reacts with methane to yield carbon monoxide andhydrogen. These two reactions are reversible in nature:

CH₄+H₂O

CO+3H₂

The reaction is endothermic and requires the input of large amounts ofheat in order to be sustained. Heating gas accounts for 80% of the totalprocess gas requirement.

A common type of hydrogen reformer furnaces is known as a “top down,” or“down fired” furnace. FIG. 1 is a perspective cut-view of a conventionalhydrogen reformer furnace 800. Natural gas burners (not shown) arespaced at the top of the furnace 800 in between rows (also known aslanes) of catalyst pipes 70, and produce heat through combustion. Theburners fire downward, parallel to the hydrocarbon-steam mixture flow,direction through the catalyst tubes 70, which are centrifugally castchrome-nickel tubes that are typically 10-40 feet long, and mountedvertically in the furnace 800. The tubes 70 contain an activated nickelcatalyst on alumina carriers in the form of pellets or balls, forexample. The process gas and steam are fed downward over the catalystand removed from the bottom of the tubes 70.

The primary reformer operates at temperatures in the 700-800° C. range.The hot gas is then passed into a convective heat transfer zone, andsteam is generated and may be fed back into the primary reformer. Thisunit is used to produce synthetic fuel that may be turned into a varietyof liquid fuels for powering internal combustion engines. It is alsooften used to produce hydrogen for other processes in the plant burnerwhereby flame and hot gas radiation provide heat input to the tubes tosupport the highly endothermic reaction. The air exits out one side ofthe bottom of the furnace 800. Based on the location of the burners andthe furnace exit, the air flow and heat distribution are non-uniform. Inthis situation, it is common for the hot gasses with flow directly tothe exit, creating a cold area in the back of the unit and a hot spotjust before the exit which can reach temperatures high enough to damagethe catalyst tubes. In order to correct for this, flue gas tunnels 80are provided, which act as collection ducts for the combustion gases,promoting even heat distribution in order to improve efficiency andprolong the life of the tubes 70.

While SMR is a well-established process, and efforts have been made overtime to optimize many facets of the technology in order to increaseefficiency, most of the focus has been centered on improving aspects ofthese reformers with respect to the catalyst, metal alloys, burners,feed stocks, etc. However, one piece of SMR technology has beencompletely ignored where advancements are concerned. That is, therefractory designs used in the construction of these units have remainedstagnant for decades. In particular, the flue gas tunnels whichtransport combustion gasses through the fired heaters have not beenchanged despite the clear need for improvement based on performancereliability issues.

These tunnels 80 average about 8 feet in height, 3 feet in width and runthe full length of the furnace unit 100 (e.g., 40 ft-50 ft). Because ofthe size of these tunnels 80 and the volume of refractory materials usedin their construction, they have traditionally been fabricated usingbasic brick shapes (e.g., standard rectangular shapes, shown in FIG. 2),in a similar manner to constructing any structural brick wall. The walls81 of the tunnels 80 are then topped with a series of rectangular blocks82 that form a lid (see, e.g., FIGS. 1-3). Historically, conventionaltunnel walls 81 have been very prone to mechanical failure under heatand over time. The main modes of failure for these flue tunnels arerelated to refractory design, installation technique, mechanical abusein service, and initial material selection.

Even though they are problematic, these tunnels 80 are essential inorder for the furnace unit 800 heat evenly and achieve the requiredefficiency. For example, if a down fired reformer did not include suchtunnels 80 in its unit construction, all of the combustion gasses wouldrush into the flue at the exit of the reformer. This would create uneventemperatures throughout the unit with cold areas away from the flue andhot spots near the exit of the unit, as discussed above. As a result,the reformer would not only experience reduced efficiency, but wouldalso overheat the catalyst tubes near the exit, causing prematurefailure to occur.

The design and construction of conventional flue gas tunnels 80 in SMRsinvolves the use of flat bricks with typical dimensions of 3 in×9 in×6.5in. The walls 81 are constructed so that half blocks are left out inregular patterns to allow for gas passage through the wall 81 into thetunnel 80 (not shown). Typically, the bricks are mortared in placeduring construction in order to hold the walls 81 together. A commonalternative to the standard flat brick is a standard tongue and groovebrick 83, 84 (see, e.g., FIGS. 4 and 5). While many sizes andconfigurations of these types of bricks exist, such conventional brickstypically use a simple tongue and groove feature to mechanically engageeach other when vertically stacked in the common manner. As shown inFIGS. 4 and 5, conventional bricks 83, 84 include simple tongue 832, 842and groove-style mating features 833, 843 that fit together whenvertically stacked.

In the past, in conventional tunnel structures, large expansion gapshave been provided, located every 6-10 ft along the tunnel walls inorder to account for thermal expansion in the system. The expansion gapis a critical aspect of design and construction, because the anticipatedthermal growth must be accommodated. In this case, however, due to thepresence of these large expansion gaps, every tunnel is actually made upof several large free-standing walls. In order to help support thesefree-standing sections of tunnel wall, intermediate support walls orpilasters are therefore also provided (not shown). These intermediatesupport walls connect the outer walls of tunnels between catalyst tubesin order to prevent the walls from leaning or collapsing. Pilasters,also known as buttresses, serve the same purpose, and are structured ascolumns of bricks located outside of the tunnel walls (not shown).

Another feature of the tunnel wall construction is the end wall (notshown). Also known as cross-over walls or target walls, these brick wallsegments connect tunnels at the exit of the unit, preventing gas by-passthrough the surrounding lining. In addition to providing additionallateral support, the end walls also ensure that all combustion gassesproperly exit through the flue gas tunnels 80.

Once the tunnel walls are constructed, the tunnel covers (lids) areplaced on top. These covers, often called coffin covers, are typicallymade from large slabs of refractory material. However simple the designmay be, they serve an important purpose, because failed covers decreasethe unit efficiency, cause tunnel wall failure as they fall, andcontribute to shorter tube life. There are four main styles of coffincovers. The main style is a rectangular or square solid design (see,e.g., lid 82 in FIG. 3). This represents the traditional approach, andis simply a solid slab of refractory material that spans the horizontaldistance (gap) between walls 81. These solid covers 82 can also have anotched surface or otherwise be formed with a mating feature on thebottom or sides that can mechanically engage with the tunnel walls andprovide additional support (not shown). Another style is the hollow orextruded lid 821 (see, e.g., FIGS. 6 and 7). These types of covers 821have the same outer dimensions as the rectangular solid lid 82, butinclude a pair of hollowed-out sections (cavities) 822 in the middle toreduce the weight of the lid and the resulting stresses.

Another common cover design is the off-set cover 831, as shown in FIG.8. This solid lid features a slanted geometry that facilitatesengagement between adjacent covers, which offers extra support duringupsets and which can help support cracked lids in the event of a coverfailure. FIG. 9 shows a tongue and groove cover 851, which is a anotherversion of the off-set cover 831, but whose mechanical mating features(i.e., tongue 851 a, and groove 851 b) provide even more engagement withadjacent lids 851.

One of the current types of failures seen in the field is the collapsingof a section of lids, or all of the lids, over the entire length of thetunnel. Once installed, the lids act as a beam, and a crack in themiddle of the lid is often the result of the ratio between the span andthe material thickness. The cross-section (thickness) of the replacementlids is then increased, but after another campaign, the failure istypically even worse than before. This is because the lid failure is nota result of static load. Hand calculations coupled with computersimulation have shown that the static load alone imparts very littlestress on the lids, and will not result in a failure. Computer runfinite element analysis (FEA) of a 9 in W×9 in T×42 in L solidrectangular lid (see, e.g., FIG. 3) installed on a tunnel at a constantservice temperature of 1900° F. demonstrated that the lid has noexternal forces acting upon it other than its own weight. The result isa maximum stress of a very modest 10 psi.

With many materials, the modulus of rupture (MOR) decreasessignificantly at higher temperatures, and it is possible to select a lowgrade refractory lid material whose MOR decreases at operationalexcursion temperatures to a point that even the mild stresses associatedwith the static load can result in failure. However, most engineeredrefractory material suppliers characterize the hot modulus of rupture(HMOR), and supply a material option for lids that have a high enoughHMOR so that even with the decrease in strength, the static loads stillhave a very significant factor of safety associated therewith. Based onthe comparison of the FEA results to the published HMOR, it has beenconcluded that most lid failure is not a result of static load alone,and is therefore a result of stresses associated with the thermal state.

Thermal stresses in such a situation manifest several ways. One way thecomponents can fail is if the thermal expansion is not properly managed,resulting in excessive compressional force. Since the lids are placed ontop of the wall sections and the only constriction is either friction ormortar, the thermal expansion will not be constricted to the point offailure. The HMOR of commonly used refractory mortars is roughly 500psi, well below that of the refractory material selected for the tunnellid, so if the thermal stresses reach that level, the mortar will breakand the lid will be free to expand as necessary.

The component can also fail as a result of thermal stress that occurs asa result of any temperature differential incurred during operation, andis not limited to instances of large upsets. Thermal stress failureresults when the thermal expansion from one area of a component isdifferent from another area resulting in a stress greater than the yieldstrength of the material. If the temperature in the convection sectionof the furnace is different than the temperature inside the tunnels,even for a short period of time, the potential for thermal stress ispresent. FEA of a 9 in W×9 in T×42 in L solid rectangular lid (see,e.g., FIG. 3) installed on a tunnel with a temperature on the topsurface of the lid at 1910° F. and a temperature on the bottom surfaceof the lid at 1900° F. has shown that the lid has no external forcesacting upon it, other than its own weight. A differential temperature of10 degrees across the lid results in a max stress of 1500 psi, which isabove the HMOR of lower end refractory materials. In a situation where avery large number of the lids of a tunnel all failed during the samecampaign without any of the walls collapsing, it is most likely that themode of failure was thermal stress.

Another important factor in the performance of the tunnel lids is thematerial's creep resistance. Creep occurs when a material slowly butpermanently deforms under long term exposure to high levels of stressthat are below the material yield strength. The result on the tunnelwalls is a transmission of the lids mass in the vertical direction,which compliments the strength and structure of the wall. Creep of a lidwill result in a “sagging” of the center span and will change theinteraction force between the lid and the tunnel walls, and eventuallylead to a failure. Creep can be characterized with ASTM standardtesting, which is representative of the use of a tunnel lid in serviceand is an important component to material selection. ASTM tests on SuperDuty Brick have published results of a 7.86% deflection at 2,600° F. Theresult on the tunnel walls is a transmission of the lids mass at anangle that is a few degrees off of the vertical axis and whichencourages the walls to separate further apart from one another at thetop than at the bottom.

A full tunnel collapse can actually be the result of several differentmodes of failure. Conventional tunnel construction uses hundreds ofthousands of pounds of refractory brick and lids, all of which accountsfor mass that ultimately rests on a final base layer of insulating firebrick (IFB; not shown in FIGS. 1A and 1B). Conventional tunnelcross-sections with bricks that are 6 in wide, tunnel walls that are 96in tall, and a solid lid that is 9 in thick results in a load on thesupporting IFB layer of 11.6 psi. Published data using ASTM testingshows that at the temperatures present in the reformer furnaces, thebase IFB layer will deform a full 1% under those loads in 100 hours. Thedeformation of the base IFB layer translates in one of two ways: eitherthe deformation will prematurely compress the fiber allowances forthermal expansion, or the deformation will reduce the overall insulatingvalue of the base IFB. Both instances are known to result in failure.

The effects of temperature and tunnel mass are not limited to theinternals of the furnace, but can also cause deformation of thesupporting furnace structure, leading to a non-uniform furnace floor.Conventional tunnel designs utilize mortared joints to secure the bricksto one another, effectively turning the large number of small bricksinto a small number of large wall sections. These wall sections act as asingle body, and cannot accommodate any major dimensional change in thefurnace floor. Deformation of the supporting furnace structure willtherefore result in the failure of a conventional tunnel.

Differential thermal expansion occurs not only in situations withdifferent design materials, but also across large sections of materialsthat are expected to act as a single body. Conventional tunnel designalso uses fiber expansion joints roughly every 6-10 feet of wall length,with all of the building components in between adhered to one anotherwith a refractory mortar. This refractory mortar also causes the wallsections to behave as a single body. No furnace has a completely uniformtemperature distribution, however, and at some point, differentialthermal expansion will occur across a wall section. The stressesimparted on the wall section are the same as those that cause thermalshock within a singularly body.

FEA has been performed to determine stress levels associated with adifferential temperature from the top of a fully mortared 10 ft wallsection to the bottom, where the fully mortared wall section was treatedas a single body for the purposes of the analysis. The bottom of thewall section was 1925° F. and the top of the wall section was 1900° F.,with a uniform temperature distribution in between. The FEA alsoincluded a simulated weight of the tunnel lids and gravity, but no otherexternal forces. It was shown that the stress of the system exceeds the500 psi HMOR of a standard refractory mortar. Since the mortar jointsare the weakest point on the wall, they crack to alleviate the stress.The more cracking that occurs in the mortared wall, the smaller the wallsections become, and the lower the stresses become in any one section.

Properly accommodating for thermal expansion is one of the mostdifficult aspects of any thermal application design. Conventional tunneldesigns use a different materials and designs for the tunnel lid and thetunnel base. Many tunnels have low density refractory or fiberinsulation in the “base” area in between the wall supporting IFBcolumns. The tunnel lid can expand as much as ⅜ in, thereby pushing thetunnel walls apart, whereas the fiber insulation will not impart anyexpansion forces on the tunnel walls. The resulting trapezoidal shape issusceptible to buckling and collapsing. In certain situations, tunnelshave been found at the conclusion of a furnace campaign to havealternative movement in the lateral direction. This is more commonlyknown as “snaking,” and is the result of the overall tunnel attemptingto expand greater than the built-in allowance. This movement will crackthe mortar, separate the walls from lids, and push the walls off of theIFB base; all of which lead to failure. While traditional tongue andgroove brick design with a circular cross section (see, e.g., FIGS. 4and 5) is somewhat effective in preventing lateral movement, thisarrangement does will not sufficiently arrest buckling, as the rotationof one block relative to the block below it will separate the tonguefrom the groove, allowing a full system collapse (see, e.g., FIG. 15).

In addition to the above problems with the traditional wall design andcomponents themselves, installing a conventional tunnel system requiresa number of skilled labor positions that are becoming increasinglychallenging to fill, particularly for temporary needs. This oftencreates a situation where the proper level of skilled labor is notavailable, and the overall quality of resultant installed tunnel systemis compromised or the installation costs become higher than expected. Insome instances, a conventional tunnel system has simply operated for thefull amount of its originally projected life span, but due to short timeframe of a turnaround schedule the tunnel cannot be fully repaired orreplaced and must continue to perform for an extended campaign. Thelength of time and the high skill level required to install aconventional tunnel system therefore becomes a cause for the reliabilityissues. The full extent of damage that may be imparted to a tunnelsystem is often unknown prior to a turnaround, so a maintenanceengineering crew has only a few weeks to examine, design, and implementrepairs that are meant only to keep the tunnel system operational untilthe next turnaround, where this kind of repair can be attempted again.This is can be a very dangerous gamble for a plant, based on the longlead time and installation time associated with replacing the tunnelswhen a failure results in an unplanned outage.

The extended time frame and high level of skill required forinstallation and repairs imparts undesirable variability in qualityoutput for conventional tunnel systems. Repairs that end up takinglonger than the available window of plant turnaround time are not aviable option, and often result in an undesirably extended tunnelcampaign. There is a strong desire to reduce the overall installationtime and need for highly skilled labor in order to decrease thisvariability in quality. In some cases, conventional tunnel systemsrequire overhead cranes to be installed to assist in the handling of theheavy tunnel lids.

In addition, in some cases, the end user may seek to add supplementalmembers to reinforce the tunnel wall structure and/or control the gasflow dynamics within the tunnel chamber in order to achieve improvedefficiency, higher throughput or other specific results.

In order to control the gas flow, in the past, the tunnel design hasbeen modified to exclude a brick or a half-brick from the array toprovide the openings in the specific locations needed to achieve theobjective, as discussed above. This conventional system, however, hasmuch room for improvement. U.S. Pat. No. 8,439,102 discloses vectortiles that are used in conjunction with diffusor walls in reactionfurnaces to control the gas flow direction, however, these vector tilesare not used in the sidewalls of hydrogen gas reformer flue gas tunnels,and since these vector tiles are cemented in place, they are not easy toinstall or fix in situ as the situation may demand.

To date, the prior art does not include any universally applicablerefractory insert members that can be easily installed in the openingsin the blocks in any location(s) desired by the end user toreinforce/strengthen the structural integrity of the tunnel and/orcontrol the flow dynamics in any manner that is required for anyparticular type of application.

SUMMARY OF THE INVENTION

The object of the present invention is to provide refractory insertmembers for use in a light-weight, free-standing tunnel structure,preferably constructed without the use of mortar, that better withstandsthe application of hydrogen reformers, using more mechanically robustrefractory components that are made of higher performance material. Morespecifically, it is an object to the present invention to overcome thedrawbacks of the prior art by providing one or more refractory insertmembers that are installed in openings of the blocks to providerefractory block assemblies that offer improved structural stabilityand/or control the gas flow conditions in such a tunnel system.Preferably, the refractory insert members are used in conjunction withlight-weight, structurally stable parts in system designs which avoidputting individual components into tension, and which include a networkof evenly distributed, highly engineered expansion gaps that ensure thecorrect amount of room for thermal growth, but which do not require anyprecision measurement at installation.

According to one aspect of the present invention, a refractory blockassembly is provided, comprising a refractory block having at least oneopening formed therein, and at least one refractory insert member thatresides within the at least one opening in the refractory block. Therefractory insert member comprises mechanical mating member that engagesa corresponding mechanical mating member provided on an inner surface ofthe at least one opening in the refractory block. The mechanical matingmember of the refractory insert member preferably comprises a slot andgroove (channel) that mechanically engage and retain a corresponding tabprovided on the inner surface of the at least one opening of therefractory block. The at least one refractory insert member can be atleast one (one or more) of a gas flow changing plug, a gas flowrestricting puck, a gas flow changing cap, and a tie bar cradle, forexample.

According to another aspect of the present invention, a refractory blockassembly for a steam reformer furnace tunnel is provided. The refractoryblock assembly comprises a hollow main body portion having an outerperipheral surface defining a first end, an opposed second end, an uppersurface, an opposed lower surface, a first side and an opposed secondside, at least one through-hole having openings formed in the first sideand the opposed second side of the main body portion, and a refractoryinsert member that resides within at least one of the at least onethough-hole, the refractory insert member comprising a mechanical matingmember that engages a corresponding mechanical mating member provided onan inner surface of the at least one through-hole. The hollow main bodyincludes at least one first mechanical mating portion defining aprotruded portion extending from a portion of the upper surface of themain body portion, and at least one second corresponding mechanicalmating portion defining an opening corresponding to the protrudedportion formed in a portion of the lower surface the main body portion.Preferably, the mechanical mating member of the refractory insert membercomprises a slot and groove that mechanically engage and retain acorresponding tab provided on the inner surface of the at least onethrough-hole.

According to another aspect of the present invention, a refractoryinsert member is provided, comprising a main body part having a firstend, an opposed second end, and an outer peripheral surface, and amechanical mating member provided on at least a portion of the outerperipheral surface. According to one aspect, the mechanical matingmember comprises at least one slot. According to another aspect, themechanical mating member comprises at least two diametrically opposedslots. According to another aspect, the mechanical mating membercomprises at least one flange having at least one slot and a channel(groove), open to the slot, extending around at least a portion of theouter peripheral surface of the main body. Preferably, the mechanicalmating member comprises at least one flange having two diametricallyopposed slots and a groove (channel), open to the slots, and extendingaround at least a portion of the outer peripheral surface of the mainbody between the slots. According to another aspect, the mechanicalmating member comprises two parallel flanges, separated from one anotherby the channel located between the flanges, and at least one of theflanges has two diametrically opposed slots open to the channel, whereinthe channel extends around at least a portion of the outer peripheralsurface of the main body between the slots. The refractory insert membercan be one of a gas flow changing plug, a gas flow restricting puck, agas flow changing cap, and a tie bar cradle, for example.

According to another aspect of the present invention, a refractorytunnel assembly for a steam reformer furnace is provided. The tunnelassembly comprises a plurality of hollow base components, each the basecomponent comprising a plurality of corresponding mechanical matingmembers, and a plurality of hollow wall blocks, each the wall blockcomprising a plurality of corresponding mechanical mating members thatfurther correspond to the mechanical mating members of the basecomponents, wherein at least a portion of the plurality of wall blocksfurther comprise at least one through-hole having openings formed inopposed side surfaces thereof. The tunnel assembly further includes aplurality of hollow lid components, each the lid component comprising aplurality of mechanical mating members that further correspond to themechanical mating members of the base components and the wall blocks,and one or more refractory insert members that reside within one or moreof the though-holes in the wall blocks. The base components are arrangedto extend in a horizontal arrangement direction defining a width of thetunnel assembly and a longitudinal arrangement direction defining alength of the tunnel assembly. The wall blocks are stacked upon andmechanically interconnected to the base components via the correspondingmechanical mating members, without the use of mortar, in a verticalarrangement direction and along the longitudinal arrangement direction,and are stacked upon one and mechanically interconnected to another viathe corresponding mechanical mating members, without the use of mortar,in both the vertical and longitudinal arrangement directions, to definetwo parallel tunnel walls, spaced a distance apart from one another inthe horizontal arrangement direction, wherein the tunnel walls extendupwardly from the base components in the vertical arrangement directionand along the length of the tunnel assembly on the base components. Theplurality of lid components are stacked upon and mechanicallyinterconnected to the wall blocks via the mechanical mating members,preferably without the use of mortar, in the vertical arrangementdirection and along the longitudinal arrangement direction, so that thelids extend along the longitudinal arrangement direction and thehorizontal arrangement direction in order to cover the distance betweenthe tunnel walls along at least a portion of the length of the tunnelassembly.

Preferably, the base components, the wall blocks, the lid components,and the refractory insert members all comprise the same material.According to one aspect, the tunnel assembly further comprises at leastone tie bar extending between the tunnel walls in the horizontalextension direction and having a first end located in a portion of afirst refractory insert member and a second end located in a portion ofan opposed second refractory insert member. The at least one refractoryinsert member preferably comprises a mechanical mating member thatengages a corresponding mechanical mating member provided on an innersurface of the at least one through-hole of the wall blocks. Accordingto one aspect, the mechanical mating member of the refractory insertmember comprises a slot and groove (channel) that mechanically engage acorresponding tab provided on the inner surface of the at least onethrough-hole of the wall blocks.

Thermal stresses associated with a temperature differential across abody can result in failure from thermal shock. There are a number ofapproaches that are utilized to reduce the thermal stresses below theyield strength of a refractory component. Decreasing the wall thicknessof the refractory component allows for the thermal conductivity of thematerial to equalize the wall temperature and eliminates the stressesassociated with the thermal differential. The wall thickness should beas thin as possible without sacrificing the overall stability of thetunnel system. Since the tunnel system is only self-supporting, reducingthe wall thickness of all of the components also decreases the overallsystem weight.

Providing the optimal wall thickness is achieved by the proper balanceof strength and weight. Thinner walls reduce thermal stresses and systemweight, but thicker walls can support more load. As described inPCT/US15/34330, the entirety of which is incorporated herein byreference, the wall thickness is preferably in a range of about 0.5in-1.5 in, most preferably in a range of 0.625 in to 0.875 in. Thedesired weight for each component is specified herein, and is about 40lbs-60 lb for the blocks, 50 lb-75 lb for the lids, and 60 lb-100 lb forthe bases.

In addition to reducing the wall thickness of the individual components,the “sections” of the tunnel system are reduced so that the differentialtemperature seen by a single section is minimized. Ideally the“sections” of the tunnel system should only be as large as theindividual building components. In order to accomplished this, everyblock must manage its own thermal expansion, and the entire system mustbe mortar-free, but for stability maintenance, must be completelyinterconnected. This is accomplished by providing precision formed,robustly mechanically inter-connectable refractory components, and aninstallation procedure that automatically accommodates for thevariability in each component.

In order to ensure proper thermal expansion management, the tunnelsystem also utilizes a base component that is made of the same materialand has substantially similar dimensions with respect to the lid (cover)component. This ensures that the tunnel expands and contracts equally onboth the top and bottom of the wall, maintaining the overall structureand reducing stresses that could otherwise cause buckling. Buckling canalso be arrested by virtue of the robust and tight toleranceinterlocking mechanical mating feature provided in the wall components,so that the rotation of a block in relative to a block below it does notbreak direct contact.

Even if the thermal expansion is properly managed, in order to furtherprevent buckling from still being an issue as a result of delayedignition or a non-uniform furnace floor, cross-beam supports or tie bar(tie rod) supports are also provided at predetermined locations inconnection with an associated refractory insert member (i.e., a tie barcradle insert member).

Other refractory insert members, such flow restricting/constrictingplugs and flow directing caps, can also be installed in variouslocations throughout the tunnel array to control the flow dynamics inany intended manner. Any of the various refractory inserts according tothe present invention can be used in conjunction with any opening/holelocation in any of the bricks of the tunnel system. This provides amodular system and allows for a universal refractory insert-mating tabto be provided on the surface of the openings (through-holes) of blocks(bricks) that can be used in conjunction with any type of refractoryinsert member in any location in the tunnel. Such flexibility allows theend user to modify the installation of refractory insert members in anymanner that they deem necessary, depending on the particular processingconcerns that they may face.

While the refractory insert members according to the present inventionare preferably used in conjunction with the reduced-weight refractoryblocks also described herein, it should be noted that the refractoryinsert members according to the present invention can likewise bereadily inserted in conjunction with standard bricks and standard bricktunnels. In that case, for example, a standard brick or a pre-cast bricksized piece can be modified to include a through-hole having amechanical mating feature (e.g., a tab) that is either pre-formed on(i.e., machined or cast) or later added onto (adhered) the inner surfacethereof to engage the refractory insert member in the same mannerdescribed herein.

Proper material selection and installation procedures are also importantto prevent “snaking.” Many materials will increase in overall dimensionwhen re-heated, increasing variability and adding challenge to thethermal expansion management. Because the coefficient of thermalexpansion for refractory components is nonlinear, it must be fullycharacterized and understood to ensure that proper expansion joints arecreated. Selecting a suitable material has always been about compromiseand sacrifice in connection with conventional tunnel designs. That is,conventionally, bricks that have sufficient insulating value to keep thefurnace supports from deforming do not always also have enough strengthto adequately support the tunnel system, and bricks with higherstrengths do not have the required insulating value. Conventionalmaterials include various types of fire bricks and super duty brick.

The coefficient of thermal expansion (CTE) for the selected materialshould not simply be assumed as a linear function for the materials usedin the tunnel system. Having a fully characterized CTE is preferable forensuring that the expansion behavior is properly managed. This becomeseven more critical when the thermal expansion is managed on a singlecomponent level. Proper material selection preferably includesconfirming that the modulus of rupture at the service and excursiontemperatures of the furnace has a sufficient safety factor when comparedto the associated static load stresses. Selecting a material with animproved HMOR provides immediate increases to the safety factor in thesystem. Knowing the room temperature MOR of a refractory material aloneis not sufficient for proper design of a tunnel system.

In addition, any material being selected for use in a reformer furnaceshould preferably have the highest resistance to creep reasonablyavailable, as a reduced creep will prolong the life of the tunnel systemand prevent premature failures. The use of a material with improvedcreep resistance reduces the tension on the bottom side of the top lids,and reduces the outward force that the top lids exert onto the brickwalls of the tunnel, which is preferred. Using a material having a fullycharacterized CTE, higher HMOR, and increased creep resistance togetherimproves the overall reliability of the tunnel system.

In view of the above, in the present invention, suitable materials forthe bricks (blocks), bases, the covers (lids) and the refractory insertmembers include, but are not limited to alumina-based refractorymaterials, cordierite (magnesium aluminum silicate), and zirconia, forexample. More preferably, the blocks, lids and bases are made from amaterial selected from the group consisting of medium duty fire claybrick (Oxide Bonded Alumina comprised of at least 30% alumina byweight), high duty fire clay brick (Oxide Bonded Alumina comprised of atleast 35% alumina by weight), super duty fire clay brick (Oxide BondedAlumina comprised of at least 40% alumina by weight), and high aluminafire clay brick (Oxide Bonded Alumina comprised of at least 60% aluminaby weight). Most preferably, the present invention utilizes MulliteBonded Alumina comprised of 88% alumina by weight or an Oxide BondedAlumina comprised of 95% alumina by weight.

The tunnel also utilizes a base component that distributes the weightload of the wall over an area that is roughly 5 times larger than theconventional design. The light-weight design of the present invention,coupled with the inventive base component, typically results in a loadon the base layer of 1.4 psi. This allows for the use of highlyinsulating materials, which improves the overall reliability of thestructural furnace supports and therefor the overall system.

As mentioned before, a conventional tunnel cross-section, with bricksthat are 6 in in width, tunnel walls that are 96 in tall, and a solidlid that is 9 in thick, results in a load on the supporting IFB layer of11.6 psi and a deformation of 1% within the first 100 hours of thecampaign. Decreasing the overall weight of the entire tunnel system by60% translates into a significantly lower PSI load, and results in anorder of magnitude less deformation to the base layer, thus increasingthe effective production life and efficiency of the tunnel.

With reduced wall thickness and improved materials, the light-weighttunnel lids can be easily installed or removed by two laborers. Inaddition, the light-weight, mortar-free block design with interlockingcomponents is easily handled by one laborer, and the tunnel structurecan assembled, repaired and/or disassembled as necessary withoutsignificant consequence or the requirement for high levels of skill. Therefractory insert members according to the present invention canencompass any desired type of component, including but not limited toflow constricting/restricting plugs, flow directing cups and cradles forcross beam supports (i.e., tie bars), and can be easily added to theblocks (to define a block assembly) or removed from the blocks withoutlimiting access to other tunnel components during turnarounds, ensuringthat repairs can be complete and effective. Faster installation andrepair time also allows for proper repairs to be made more readily,improving the overall reliability of the system.

Reducing the weight of the components, while maintaining the structuralintegrity of the building blocks, makes it possible to eliminate much ofthe crushing force on the lower courses of the brick. Providinglight-weight, structurally correct cover (lid) segments overcomes thedrawbacks previously associated with making those components thicker inorder to be stronger, which also detrimentally added additional load tothe entire system. The incorporation of expansion gaps between eachbrick and elimination of mortar from the system ensures that theassembly can expand and contract without the creation of largecumulative stress, and reduces the installation time of the tunnel as awhole. Providing universal, modular refractory insert members and blockassemblies in connection with any type of block further enables endusers to modify the system and custom tailor the flow dynamics accordingto their particular needs.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and object of the presentinvention, reference should be made to the following detaileddescription of a preferred mode of practicing the invention, read inconnection with the accompanying drawings, in which:

FIG. 1A is a perspective cut-view of a conventional hydrogen reformerfurnace, and FIG. 1B is a sectional end view of the furnace shown inFIG. 1A;

FIG. 2 is a perspective view of a conventional tunnel assembly used inthe furnace shown in FIGS. 1A and 1B;

FIG. 3 is a perspective view of a conventional solid lid;

FIG. 4 is a perspective view of a conventional single tongue and grovetype block (brick);

FIG. 5 is a perspective view of a conventional double tongue and grovetype block (brick);

FIG. 6 is an end view of a conventional hollow lid;

FIG. 7 is a perspective view of the conventional hollow lid shown inFIG. 6;

FIG. 8 is a perspective view of a conventional off-set lid;

FIG. 9 is a perspective view of a conventional tongue and groove lid;

FIG. 10 is a perspective top view of a half block (brick) according toone aspect of the present invention;

FIG. 11 is a perspective top view of a full block (brick) according toone aspect of the present invention;

FIG. 12 is a perspective bottom view of the full block shown in FIG. 11;

FIG. 13 is a sectional end view of two blocks shown in FIG. 11 in astacked arrangement;

FIG. 14 is a sectional end view of the stacked arrangement shown in FIG.13 under rotational force to illustrate that the stacked blocks to notdisengage;

FIG. 15 is an end view of prior art blocks shown in FIG. 4 underrotational force to illustrate that those blocks do disengage under thesame type of rotational force;

FIGS. 16A and 16B are perspective views of a full block including atleast one though-hole (two as shown) according to the present invention,and FIG. 16C is a cut-view of the full block shown in FIGS. 16A and 16B;

FIG. 17 is a perspective top view of a full width base componentaccording to the present invention;

FIG. 18 is a perspective view of a tie bar (tie rod);

FIG. 19A is a perspective view of a tie bar cradle insert member 15according to one aspect of the present invention, FIG. 19B is aperspective view of the full block shown in FIGS. 16A-C and a tie rodcradle insert member 15 being inserted therein, and FIG. 19C is aperspective view of the assembly including the installed tie bar cradleinsert member 15, FIG. 19D is a perspective view of the full block shownin FIGS. 16A-C and a tie rod cradle insert member 151 according toanother aspect being inserted therein, and FIG. 19E is a perspectiveview of the assembly including the installed tie bar cradle insertmember 151.

FIG. 20 is a perspective view of two full blocks according to FIGS.16A-C and a tie rod according to FIG. 18 situated in the respective tiebar cradles 15 defining an assembly and spanning the horizontal distancebetween the opposed blocks;

FIG. 21A is a perspective view of a flow constricting plug insert member130 according to one aspect of the present invention, FIG. 21B is aperspective view of a flow constricting plug insert member 136 accordingto another aspect of the present invention being installed in the block100 shown in FIG. 16, and FIG. 21C is a front view of the installationprocess shown in FIG. 21C, FIG. 21D is a is a perspective view of a flowconstricting plug insert member 230 according to another aspect, FIG.21E is a is a perspective view of a flow constricting plug insert member330 according to another aspect, and FIG. 21F is a is a perspective viewof a flow restricting plug insert member (puck) 430 according to anotheraspect;

FIG. 22A is a perspective view of a flow directing cup insert memberaccording to the present invention and a block shown in FIG. 16, andFIG. 22B is a perspective view of the flow directing cup insert memberinstalled in the block;

FIG. 23 is a perspective top view of a lid;

FIG. 24 is a perspective bottom view of the lid shown in FIG. 23;

FIG. 25 is a perspective view of a tunnel assembly according to thepresent invention;

FIG. 26 is a side view of the tunnel assembly shown in FIG. 25;

FIG. 27 is an end view of the tunnel assembly shown in FIGS. 25 and 26;

FIG. 28 is a perspective view of the tunnel assembly shown in FIG. 25with some wall blocks removed to show the location of the tie bars; and

FIG. 29 is a perspective view of the tunnel assembly shown in FIG. 25built up higher and having double lids.

DETAILED DESCRIPTION OF THE INVENTION Blocks (Also Referred to HereinInterchangeably as Bricks)

The flue gas tunnel according to the present invention comprises aplurality of refractory blocks or bricks, which are used in conjunctionwith one or more refractory insert members to define a refractory blockassembly. While standard bricks or pre-cast brick shaped members can beused, as noted above, the refractory blocks are preferably engineeredwith precision interlocking mechanical mating features to facilitatestacking interconnection to form the free-standing tunnel walls withoutthe use of mortar. These mechanical mating features are alsospecifically designed to allow for thermal expansion in service whilesimultaneously preventing the wall from becoming disassembledprematurely.

One example of a mating feature has a geometry that requires horizontalinstallation and prevents the block from becoming disassembledvertically. FIG. 10 shows a “half brick” 1 and FIG. 11 shows a “fullbrick” 10. FIG. 12 is a bottom view of the full brick 10 shown in FIG.11. It should be understood that the corresponding bottom view of thehalf brick 1 shown in FIG. 10 (not shown) would be same as that shown inFIG. 12, only half the size. A standard brick has dimensions of, forexample, 6.5 in W×18 in L×10 in T (tall), but the design is applicablefor bricks as small as 2 in W×4 in L×2 in T and for bricks as large as 9in W×24 in L×18 in T, as well. Preferably, each block (brick) has aweight in a range of 20-70 lb, more preferably 40-50 lb, so that oneperson can readily maneuver the blocks alone, while reducing the totalnumber of blocks needed to construct the tunnel wall to the smallestnumber possible.

It should be noted that although the blocks 1, 10 as shown do notinclude any through-holes, either type of block 1, 10 can be modified ormanufactured to include one or more though-holes, as discussed below inconnection with FIGS. 16A-1C. An example of a half-block 1A including atleast one though-hole (and having a refractory insert member installedtherein) is shown and described below in conjunction with the refractoryblock assemblies and tunnel assembly structure of FIGS. 25-29.

Each of the bricks 1, 10 has an outer peripheral surface defining afirst end (1 a, 10 a), an opposed second end (1 b, 10 b), an uppersurface (1 c, 10 c) and an opposed lower (bottom) surface (1 d, 10 d).These bricks 1, 10 are hollowed out to remove all possible material fromnon-critical areas. Preferably, the wall thickness “t” (see, e.g., FIG.12) walls of these bricks 1, 10 is in a range of 0.5-1.5 in, preferably0.625-0.875 in. The resultant tunnel assembly has only about 60% of theweight of a conventional tunnel. The hollowed-out portions define one ormore, preferably a plurality of cavities 2 in the respective blocks 1,10.

The upper surfaces 1 c, 10 c of the blocks 1, 10 each include a malepart of the precision interlocking mechanical mating features of therefractory blocks according to the present invention. The protrudingportion 3 is elevated a distance from the surface 1 c, 10 c to define ageometrical member that extends from the block 1, 10 and serves as alocking part that fits precisely into the opening 4 formed in the lowersurface 1 d, 10 d of the blocks 1, 10. As shown, the protruding portion3 is a substantially rectangular elevation with chamfered corners and acircular opening 3 a passing through its center and in communicationwith a cavity 2. The circular opening 3 a is merely a function ofmanufacturing and material removal considerations, and is not critical.As shown in FIGS. 10 and 11, the openings 3 a are in communication withthe cavities 2. This is not always the case, however, as described inmore detail below.

While the exact shape of the protruding portion 3 is not necessarilylimited to the shape shown here, it is preferably a geometric match tothe shape of the corresponding opening 4, with a slight off-set toaccommodate manufacturing tolerances. The protruding portions 3 of theblocks 1, 10 must fit precisely within the openings 4 of the verticallyadjacent blocks 1, 10 to securely engage the vertically adjacent blocks1, 10 to one another to facilitate the construction of free-standingtunnel walls without the use of mortar. There must also be sufficienttolerance to account for the thermal expansion considerations discussedabove, and to maintain contact to prevent buckling.

The opening 4 communicates with the cavities 2 of the blocks 1, 10, andreceives the protruding portion 3 in a tight, interlocking manner tosecurely connect the blocks 1, 10 to one another, without mortar, in avertically stacked manner, as shown in FIG. 13. The shape of the opening4 is not critical, so long as it precisely corresponds in shape and sizeto the shape and size of the protruding portions 3, in consideration ofthe mechanical factors and thermal concerns discussed above.

The importance is the geometric match with a slight off-set between thecorresponding protruding portion 3 and opening 4 into which theprotruding portion 3 fits. Preferably, the off-set is in a range of0.020 in to 0.060 in. The minimum off-set is dictated by manufacturingtolerance capabilities resulting in block to block variability. Theremust be sufficient height and tightness to securely engage if bucklingoccurs. Preferably, the overall height “h” of the protruding portion 3,or distance that the protruding portion 3 extends from the upper surface1 c, 10 c of the blocks 1, 10, is at least 0.75 in, in order to ensuresufficient engagement with the opening 4 and prevent buckling. Thedimensions of the opening 4 should be as tight to the protruding portionas possible with allowance for manufacturing variation. Ideally, uniformwall thickness balanced with manufacturing needs governs the dimensions.

The individual blocks 1, 10 further include additional mechanical matingfeatures, such as a tab on one end and a groove on the other end, with agap provided that allows each block to expand with increasing operatingtemperature until its seals against the blocks on either side thereof inthe horizontal arrangement direction. As shown in FIGS. 10-12, the firstsides 1 a, 10 a of the blocks 1, 10 include a groove or slot 5, and theopposed second sides 1 b, 10 b are formed to include a corresponding“tab” or protrusion 6 that vertically fits into the corresponding groove5 of a horizontally adjacent block 1, 10. Preferably, the groove islarger than the tab by a minimum of manufacturing variation; preferably,the tab is 30-75% of the overall width of the block.

A compressible high temperature insulation fiber (not shown) can also beprovided, placed in the groove 5 in order to reduce gas bypass whileaccommodating for a range of temperature fluctuations in service. Thefiber is specified to have sufficient compression variability so as toreduce gas bypass over a wide range of operating temperatures from 600°C.-1200° C. This fiber can also be used in between layers of blocks toprevent point loading. As discussed below, the base components and toplids (covers) both have a similar tab and groove design, and use eithera fiber gasket or a fiber braid to reduce gas bypass over the range ofoperating temperatures.

Preferably, as the blocks 1, 10 are arranged in the formation of thetunnel wall, the blocks 1, 10 are horizontally off-set by one-half of ablock length, or by one set of mechanical mating features, to increasethe mechanical robustness of the arrangement (see, e.g., FIG. 25 inconnection with blocks 1A, 10 and 100). This arrangement also helpsprevent buckling, which is arrested by virtue of the robust and tighttolerance interlocking mechanical mating feature, so that the rotationof one block relative to a block below it does not cause direct contactbetween the respective protruding portion 3 and the opening 4 to break,as shown in FIG. 14. On the other hand, FIG. 15 shows how rotationalforces on prior art tongue and groove blocks (see FIG. 4) can causeseparation between the blocks, and direct contact between the respectivetongue and groove features significantly breaks, which leads to wallcollapse.

The mechanical mating features described above add redundancy to thesystem by mechanically engaging the blocks, which prevents the tunnelwall from leaning and falling over without requiring that matingfeatures be sheared off or otherwise break through the wall of the blockto which they are connected.

In order for the tunnel to properly act as a flue for the exit of thefurnace, it must have variable inlet conditions (openings in the walls),for example, which typically allow more gas to enter the tunnel farthestfrom the exit, and less gas to enter the tunnel closer to the exit (orin any manner dictated by the processing concerns). The typicalarrangement creates a more uniform distribution of gas and temperaturein the furnace. As noted above, conventional tunnel wall designs simplyutilize half bricks to create gaps in the walls as various locations.However, such conventional half bricks create unsupported locations ontop of the square openings, creating locations for failures.

As shown in FIGS. 16A-C, the tunnel system (see FIGS. 25-59) utilizesrefractory blocks 1A and 100 that include one or more through-holes 7formed therein in order to allow gas to enter the tunnel. This designevenly distributes the load created by the through-holes 7 to thesurrounding material. The through-holes 7 can be formed when the bricks1A, 100 are initially formed (e.g., cast), or can be formed later bymachining or any suitable process.

The block 100 has an outer peripheral surface defining a first end 100a, an opposed second end 100 b, an upper surface 100 c, and an opposedlower (bottom) surface 100 d. Although a full block 100 is shown, itshould be understood that a half-block could also be used, which wouldbe the same as block 100, but only half the size (see, e.g., thedescription in connection with FIGS. 10 and 11). Like the structureshown and described in connection with shown in FIGS. 10-12, the firstsides 100 a of the blocks 100 include a groove or slot 5, and theopposed second sides 100 b are formed to include a corresponding “tab”or protrusion 6 (not shown) that vertically fits into the correspondinggroove 5 of a horizontally adjacent block 100. Preferably, the groove islarger than the tab by a minimum of manufacturing variation; preferably,the tab is 30-75% of the overall width of the block. A compressible hightemperature insulation fiber (not shown) can also be provided, placed inthe groove 5 in order to reduce gas bypass while accommodating for arange of temperature fluctuations in service. The fiber is specified tohave sufficient compression variability so as to reduce gas bypass overa wide range of operating temperatures from 600° C.-1200° C. This fibercan also be used in between layers of blocks to prevent point loading.

Preferably, as the blocks 100 are arranged in the formation of thetunnel wall, the blocks 100 are horizontally off-set by one-half of ablock length, or by one set of mechanical mating features, to increasethe mechanical robustness of the arrangement (see, e.g., FIG. 25 inconnection with blocks 1A and 10). This arrangement also helps preventbuckling, which is arrested by virtue of the robust and tight toleranceinterlocking mechanical mating feature, so that the rotation of oneblock relative to a block below it does not cause direct contact betweenthe respective protruding portion 3 and the opening 4 to break.

The through-holes 7 of the blocks 100 can have any geometry, butpreferably have a circular or semi-circular shape. The size of thethrough-holes 7 can vary from 1 in² up to substantially to the full sizeof the block 100, which is typically around 144 in², but are preferably12 in²-36 in². For example, in FIGS. 16A-16C, the though-holes 7 have adiameter of approximately 4.5 inches. Blocks 100 preferably have one ortwo through-holes 7 per block, but could have multiple holes in variouslocations to facilitate the same end result, as desired. Thesethrough-holes 7 are preferably be closed, i.e., do not communicate withthe interconnected internal cavities 2 of the blocks 100 that form aninternal area of the tunnel wall, as shown (see FIG. 16C), or instead, anumber of blocks could have through-holes that are open to the internalarea of the tunnel wall.

As shown in FIGS. 16A-16C, the opening 3 b in the protruding portion 3is simply a removed-material portion, and does not communicate with (notin fluid communication with) the cavity 2. As best shown in FIGS. 16Band C, the through-hole 7 is like a tube that passes though the cavity2, but the internal surface 7 a of the through-hole 7 is not in fluidcommunication therewith, and the through-hole 7 (though which the gassespass) is therefore closed to the cavities 2 (and therefore the internalsurface area of the tunnel wall) by virtue of the external surface 7 bof the through-hole 7.

A mechanical mating member, such as one or more tabs 8, are provided onthe inner surface 7 a (i.e., inner diameter; see FIGS. 16B, 16C) of thethrough-hole 7, to serve as a mechanical fastening feature thatinterlocks with corresponding mating features provided on variousrefractory insert members. As shown in FIGS. 16A-C, the tabs 8 arepreferably located on diametrically opposed portions of the innersurface 7 a of the through-hole 7. Although the exact dimensions of thetabs 8 are not expressly limited by anything except the correspondingmating geometry of the insert members (described below), these tabs 8have a preferred dimension of ⅜″ high (protruding from the innerthrough-hole surface 7 a), ¾″ long (axial distance), and 1.75″ wide(radially). While the size of the tabs 8 and the shape of the tab 8 canreadily be modified, it is preferred that the aspect ratio of 2:1,length: height is maintained. Preferably, the size of the tab 60° orless with respect to the circumference of the inner diameter (innersurface) 7 a of the through-hole 7, but must necessarily be onlyslightly less than the corresponding receiving part (opening/slot) onthe insert member, in order to by-pass the opening and fit therein orwithin the receiving groove (once rotated).

Base Component

The base component 30 is shown in FIG. 17. A plurality of basecomponents 30 run the length of the tunnel and span the horizontal width‘w’ of the tunnel to connect the two walls together using the samemating features as the wall blocks 10, 100 described above (see, e.g.,FIGS. 25-29).

Each base component 30 has an outer peripheral surface with an uppersurface 30 c and an opposed lower (bottom) surface 30 d on which theinterlocking mechanical mating features protruding portions 33, andcorresponding openings 34 (not shown) are respectively formed. Theprotruding portions 33 correspond to the protruding portions 3 describedabove in connection with the bocks 1, 10, 100, and the openings 34correspond to the openings 4 described above in connection with theblocks 1, 10, 100. The same critical dimensional requirements for themechanical mating members and wall thicknesses discussed above apply tothe base components, as well. Preferably, each base component 30 has atotal weight in a range of about 60-100 lb, more preferably less thanabout 70 lbs.

The protruding portions 33 are provided on the upper surface 30 a of thebase components 30 proximate the two opposed ends 30 a, 30 b, so as tocorrespond to the laterally (horizontally) opposed locations of thetunnel walls to be built thereon. The openings 34 are provided in thebottom surface 30 d of the base component 30 in corresponding locations.In some embodiments, the base component 30 has a plurality of cavitiesfrom which unnecessary material has been removed to reduce the weight ofthe base block. The openings 32 are material removed portions and may ormay not communicate with such cavities, and a plurality of additionalcavities are provided along the length of the base component 30,separated by interior block walls having sufficient thickness to provideenough material to ensure the structural integrity of the component ismaintained. The wall thickness is preferably in a range of 0.5 to 1.5in, preferably 0.625 to 0.875 in.

As noted above, it is important that the size and material of the basecomponent 30 is substantially the same as that of the lid (discussed inmore detail below) in order to properly and effectively compensate forthermal and stress factors, although the base is a heavier component, asone skilled in the art can appreciate.

Lids (Also Referred to Herein Interchangeably as Covers)

The span of the top lid 60 can be as small as 12 in, or as wide as 60in, although the preferred size is a range of 24 in to 36 in.Preferably, each lid component has a total weight in a range of 50-100lb, more preferably in a range of 60-80 lbs.

As shown in FIG. 23, the upper surface 60 c of lid 60 has a flat topwith angled sides. The upper surface 60 c of the lid also includes thesame interlocking mechanical mating features 63, 64 as described abovein connection with the blocks 1, 10, 100 and the base components 30. Inthe case of the lid 60, the protruded portions 63 serve two functions.First, the protruding portions 63 provide mechanical mating features inconnection with the corresponding openings 4 on other wall blocks 10,100 in the same manner discussed above, which enable the lid 60 to beused in an assembly where the lid 60 is not the only topmost component,but where additional tunnel wall blocks 10, 100 are instead placed ontop of the lid 60, and the walls are continued vertically upward,providing a stacked-lid arrangement (see, e.g., FIG. 29). Second, sincethe protruding portions 63 extend a distance of at least 0.5 in above(in the vertical direction) the overall surface geometry of the lid 60,this allows for the placement of a plywood board on top of the lid 60 todefine a walkway during furnace turnarounds. Because this existsdirectly above the tunnel walls, the walkway allows workers access intothe furnace on top of the tunnels without putting weight onto the centerof the unsupported span of the lids, and instead directs all of theirweight onto the tunnel walls, where it can be readily supported.

The lid 60 is also hollowed out from the bottom surface 60 d to removeall possible material from non-critical areas, in order to minimize thestress by improving the ratio of force per unit area of the crosssection. As shown in FIG. 24, a large central cavity 62 is formedthereby, as well as two smaller cavities 62 in communication with theopenings 64 defining the mechanical mating features. The mechanicalmating feature (opening) 64 provides engagement with the protrudedportions 3 of the blocks 10, 100 forming the walls 8 to securely attachthe lid 60 to the walls 8 on either side, spanning the internal tunnelwidth between wall structure. The critical dimensions of the mechanicalmating features are the same as discussed above. Preferably, the wallthickness “t” of the lids is in a range of 0.5 to 1.5 in, morepreferably 0.625 to 0.875 in.

The lids 60 also have additional mechanical mating features such as thegrooves 65 formed on side surface 30 f (see FIG. 24) and protrusion ortab 66 formed on side surface 60 e (see FIG. 23). These features servethe same purpose and function as the mechanical matingfeatures/expansion gap features 5 and 6 described above in connectionwith the blocks 1, 10, 100 described above in connection with the basecomponent 30. The position of these mating/expansion features 65, 66corresponds to the mating alignment with the other lids 60 and the wallblocks 10, 100 stacked thereunder, as described below in more detail inconnection with FIGS. 25-28.

Refractory Insert Members

As described above, the blocks 100 (or 1A) include one or more tabs 8that are added, cast or pre-formed by machining, for example, on theinner surfaces (inner diameter) 7 a of the through-holes 7 of the blocks100 (see, e.g., FIGS. 16b and 16C). The tabs 8 serve as secure matingfeatures for the specialty refractory insert members that are utilizedin the tunnel system. The refractory insert members have correspondingmating features (i.e., openings/slots and grooves) that mechanicallyengage and/or retain the tabs if rotated (described in more detailbelow).

Since the through-hole or opening in the brick (block) 1A, 100 is notlimited to the geometry of a circle, the corresponding overall geometryof the refractory insert member is therefore dictated by the overallgeometry of the respective through-hole. A circular shape (cylindrical)is preferred. Any of the various refractory insert members according tothe present invention can be used in conjunction with any through-holelocation in any of the blocks 100 to define a refractory block assembly,and likewise, and such a refractory block assembly can be used in anylocation of the tunnel system according to the present invention. Thisprovides a modular system and allows for a universal refractoryinsert-mating tab to be provided on the surface of the openings of theblocks (bricks) that can be used in conjunction with any insert in anylocation in the tunnel. Such flexibility allows the end user to modifythe installation of refractory insert members in any manner they deemnecessary depending on the particular processing concerns that they mayface.

Tie Bars (Also Referred to Herein Interchangeably as Tie Rods and CrossBeam Supports) and Tie Bar Cradle Insert Members

A tie bar is used in the tunnel assembly at various points to secure thewalls in place to prevent movement, both inward and outward, as shown inFIGS. 18, 20 and 27-29. One example of a tie bar 50 (also referred to asa tie rod or cross beam support) is shown in FIG. 18. The tie bar 50engages and supports the tunnel walls in various ways, as describedbelow. The tie bars 50 are placed at various points in the system toimprove the overall stability of the tunnels in service, as one skilledin the art can readily determine. The span of the tie bar 50 issubstantially the same as the span of the top lid and the basecomponent, which can be as small as 12 in or as wide as 60 in, althoughthe preferred size is a range of 24 in to 36 in (corresponding to theinternal width of the tunnel). It is understood that the length of thetie bar is governed strictly by the designed width of the tunnel, withclearance to allow for thermal growth. The cross-sectional diameter ofthe tie bar 50 is preferably 1-8 in, more preferably 3-4 in.

As shown in FIGS. 19A-19E, tie bar cradle insert members 15, 151according to two different aspects of the present invention arecylindrical insert members extending from a first end (15 a, 151 a)toward an opposed second end (15 b, 151 b), and having a cylindricalcentral portion (15 c, 151 c). As shown in FIGS. 19A-19B, the first end15 a of the tie bar cradle insert 15 includes an annular rim 16 having acentral groove 16 b and a pair of diametrically opposed openings/slots16 a formed therein, dimensioned to accept and receive the tabs 8, andthereby serve as mechanical mating features in conjunction with the tabs8 in the through-hole 7 of the block 100 (or 1A). A s shown in FIGS.19D-19E, the first end 151 a of the tie bar cradle insert 151 includesan a pair of parallel annular rims (flanges) 153, 155 having a centralgroove (channel) 154 b therebetween, and a pair of diametrically opposedopenings 154 a formed at least in the annular rim 153 (both 153 and 154,as shown) to accept and receive the tabs 8, and thereby serve asmechanical mating features in conjunction with the tabs 8 in thethrough-hole 7 of the block 100.

The size of the openings/slots 16 a, 154 a is preferably about 60° ormore (at least slightly bigger than the tabs 8) with respect to thecircumference of the refractory insert member 15, 151 and thecircumference of the through-hole 7, but the critical dimension isdependent mainly upon the size of geometry of the tab 8, and vice versa.One skilled in the art can appreciate the factors needed to design aproperly interlocking slot and tab mechanism in the context of thepresent invention in connection with the disclosure provided herewith.The tie bar cradle inserts 15, 151 are inserted into the through-hole 7so that the slots 16 a, 154 a by-pass the tab 8 cast on the innerdiameter 7 a of the block 100. The tie bar cradle insert 15, 151 arethen rotated a sufficient amount, preferably about 90 degrees, farenough to secure it in place in the groove 16 b, 154 b, from which itcannot readily disengage.

The respective second ends 15 b, 151 b of the respective tie bar cradleinserts 15, 151 include a semi-cylindrical portion having interiorannular rim features 152 to guide, receive and retain the correspondingannular flanges 51 at the ends 50 a, 50 b of the tie bar 50 whenvertically positioned into place therein (see, e.g., FIG. 20). Again,the design of this portion of the tie bar cradle insert 15, 151 dependson the corresponding geometry of the outer peripheral shape of theflange portions 51 of the respective tie bar 50, which could conceivablyhave differing geometrical configurations (i.e., it is not limited tothe circular-shaped flange shown in FIG. 18, but could have any kind ofpolygon-shaped or elliptical lip at the end thereof). In bothembodiments, there is a shoulder portion, such as a stopper flange 15 d,151 d provided between the central cylindrical portion 15 c, 151 c thatis housed within the though-hole 7 and the semi-cylindrical portion thatcradles the tie bar 50. The outer diameter of the tie bar cradle insertis slightly smaller than the inner diameter of the through-hole of theblock to allow for proper insertion but to substantially prevent excessgas flow around the outside of the insert.

As described above, the tie bar cradle inserts 15, 151 of the tie barassembly 101 are installed into the through-hole 7 in the block 100 sothat corresponding mating features (e.g., slots, openings 16 a, 154 a)provided on the outer section by-pass the tab 8 on the inner surface 7 aof the through-hole 7 of the block 100. The tie bar cradle insert 15,151 is then rotated far enough, preferably about 90 degrees, to fullyengage the tabs 8 within the grooves 16 b, 154 b and secure it in place(see, e.g., FIG. 19C). This defines a refractory block assembly 102(FIG. 19C) or 103 (FIG. 19E). Another tie bar cradle insert is alsoinstalled in an opposite-facing block on an opposed (facing) portion ofthe tunnel wall (see, e.g., FIG. 27), so that tie bar cradle inserts 15,151 are provided in matching locations on the inside faces of bothtunnel walls, and then a tie bar 50 (FIG. 18) is installed into thecradle that has been created thereby to define the tie bar assembly 101(including at least refractory block assemblies 102 and/or 103 and a tiebar 50; see FIGS. 20 and 27). It should be noted that anther refractoryinsert can be used in a different hole of the same block that isotherwise included in an assembly 102, 103 with the tie bar cradleinsert member according to the present invention (see, e.g., FIG. 27,wherein a tie bar assembly 101 is then added to the same blocks 100already defining refractory assemblies 104″ (including blocks 100 and aninsert 230; see also FIG. 26).

Tie bar cradle inserts 15, 151 can be installed in refractory blocks 100and positioned at various locations along the tunnel walls when thetunnel walls are built, and then tie bars 50 can be readily added duringinstallation, or later removed as needed without requiring substantialdown time or creating deleterious maintenance issues. Once fullyinstalled, this tie bar assembly 101 prevents the tunnel walls frommoving horizontally in either direction (see FIGS. 27-29).

Flow Restricting/Constricting Plugs Refractory Insert Members (Plugs)

Another refractory insert according to the present invention is referredto as a flow restricting or flow constricting plug (hereinafter referredto simply as “plugs,” or “refractory insert plugs”). As shown in FIGS.21A-F, the refractory insert plugs 130, 136, 230 and 330 are essentiallyrefractory annular rings with openings of various sizes (see, e.g.,FIGS. 21A-E) formed in the respective central portions thereof, oralternatively, solid pucks 430 (see, e.g., FIG. 21F). The refractoryinsert plugs are inserted into the through-holes 7 of the blocks 100,and which have corresponding mechanical mating features, such asopenings/slots (FIGS. 21B, 21C) or openings/slots and grooves (FIG. 21A,21D-21F) that by-pass and then mechanically engage the tabs 8 on theinner diameter 7 a of the through-hole 7 in the block 100. The outerdiameter of the refractory insert plug is slightly smaller than theinner diameter of the through-hole of the block to allow for properinsertion but to substantially prevent excess gas flow around theoutside of the insert.

As shown in FIG. 21A, according to one aspect of the present invention,the refractory insert plug 130 has a central disc-shaped portion 131with an opening 131 a in the central portion thereof to permit gas flow.An annular rim (flange) 132 circumscribes the central portion 131 anddefines a pair of opposed openings 132 b (preferably around about 60° ormore (at least slightly bigger than the tabs 8) and a groove (channel)132 a communicating therebetween. The groove (channel) 132 a isdimensioned to receive and securely retain the tabs 8. The refractoryinsert plug 130 in FIG. 21A can be installed from either the inside orthe outside of the tunnel by simply turning it sideways, inserting it sothat the opening (slot) 132 b will bypass the tabs 8 on the innerdiameter 7 a of the block 100 through-holes 7, and then rotating it farenough, preferably about 90°, into place so that the tabs 8 thensecurely reside within the groove 132 a. A refractory assembly 104(including a block 100 having two refractory insert plugs 130 installedin the through-holes thereof) is shown in FIG. 26. An example of arefractory assembly 104′ including half-block 1A with a refractoryinsert plug 130 installed in the through-hole thereof is also shown inFIG. 26.

FIG. 21D shows a refractory insert plug according to another aspect ofthe present invention. The refractory insert plug 230 has a centraldisc-shaped portion 231 with an opening 231 a in the central portionthereof to permit gas flow. The opening 231 a is larger than the opening131 a shown in FIG. 21A. An annular rim (flange) 232 circumscribes thecentral portion 231 and defines a pair of opposed openings 232 b(preferably around about 60° or more (at least slightly bigger than thetabs 8) and a groove (channel) 232 a communicating therebetween. Thegroove 232 a is dimensioned to receive and securely retain the tabs 8.The refractory insert plug 230 in FIG. 21D can be installed from eitherthe inside or the outside of the tunnel by simply turning it sideways,inserting it so that the opening (slot) 232 b will bypass the tabs 8 onthe inner diameter 7 a of the block 100 through-holes 7, and thenrotating it far enough, preferably about 90°, into place so that thetabs 8 then securely reside within the groove 232 a. A refractoryassembly 104″ (including a block 100 having a refractory insert plug 230installed in at least one through-hole thereof) is shown in FIG. 26.

FIG. 21E shows a refractory insert plug according to another aspect ofthe present invention. The refractory insert plug 330 has a centraldisc-shaped portion 331 with an opening 331 a in the central portionthereof to permit gas flow. The opening 331 a is much smaller than theopenings 131 a and 231 a shown in FIGS. 21A and 21D. An annular rim(flange) 332 circumscribes the central portion 331 and defines a pair ofopposed openings 332 b (preferably around about 60° or more (at leastslightly bigger than the tabs 8) and a groove (channel) 332 acommunicating therebetween. The groove 332 a is dimensioned to receiveand securely retain the tabs 8. The refractory plug 330 in FIG. 21E canbe installed from either the inside or the outside of the tunnel bysimply turning it sideways, inserting it so that the opening (slot) 232b will bypass the tabs 8 on the inner diameter 7 a of the block 100through-holes 7, and then rotating it far enough, preferably about 90°,into place so that the tabs 8 then securely reside within the groove 332a.

FIG. 21F shows a refractory insert plug according to another aspect ofthe present invention, also referred to as a puck. The refractory insertplug 430 has a solid central disc-shaped portion 431, without anyopenings formed therein, in order to restrict gas flow. An annular rim(flange) 432 circumscribes the central portion 431 and defines a pair ofopposed openings 432 b (preferably around about 60° or more (at leastslightly bigger than the tabs 8) and a groove (channel) 432 acommunicating therebetween. The groove 432 a is dimensioned to receiveand securely retain the tabs 8. The plug 430 in FIG. 21D can beinstalled from either the inside or the outside of the tunnel by simplyturning it sideways, inserting it so that the opening (slot) 432 b willbypass the tabs 8 on the inner diameter 7 a of the block 100through-holes 7, and then rotating it far enough, preferably about 90°,into place so that the tabs 8 then securely reside within the groove 432a.

The refractory block assembly 105 shown in FIG. 22B includes the flowdirecting cap insert member 140 installed in the block 100. Another flowdirecting cap insert 140, or a different type of refractory insertmember, can be inserted in the other through-hole 7 to define a doubleassembly within the same block.

As shown in FIGS. 21B and 21C, according to another aspect of thepresent invention, the refractory insert plug 136 has a centraldisc-shaped portion 135 with an opening 135 a in the central portionthereof to permit gas flow. An annular rim (flange) 134 circumscribesthe central portion 135 and defines a pair of opposed openings 134 b(preferably around about 60° or less with respect to the circumferenceof the puck and the through-hole 7). As shown in FIGS. 21B and 21C,refractory insert plugs 136 can be installed either from the outside ofthe tunnel, by simply sliding into place, or from inside the tunnel, byturning them sideways, inserting them so that the opening 134 bypassesthe tabs 8 on the inner diameter 7 a of the block 100 through-holes 7,and then pulling them back into place. The tab 8 will sit within theopening 134 and maintain proper orientation of the insert member. Therefractory plugs 136 can be secured in place with either compressed hightemperature fiber, or a thin bead of mortar.

The refractory block assembly 104 shown in FIGS. 21B and C includes therefractory insert plugs 136 installed in the block 100. A differentrefractory plug member, or an altogether different type of refractoryinsert member, can be substituted for one of the inserts 136 andinserted in the other through-hole 7 to define a different doubleassembly within the same block 100, or one of the inserts 136 can beremoved to define a single assembly. As shown in FIGS. 25-29, refractoryassemblies including one or more types of refractory plug members (e.g.,130, 230) in blocks 1A or 100 are referred to as refractory assemblies104, 104′ and 104″.

As shown in FIG. 21F, when the central portion of the refractory insertplugs (430) is instead entirely solid (i.e., pucks), these refractoryinsert members serve to prevent any gas flow from passing through therespective through-hole 7 in the block 100. FIGS. 21A, 21D and 21E showembodiments of plugs as annular rings with central openings of varioussizes, which dictate the amount of gas flow that will be permitted toenter the tunnel at that given location. It should be noted that theseembodiments can be designed to be inserted and fixed in accordance witheither method discussed above (i.e., the twist-lock method of FIGS. 21Aand 21D-F, or the slide-in and fix method of FIGS. 21B, 21C).

Any of the refractory insert plugs according to the present inventioncan be removed and or replaced with another refractory insert plughaving a different configuration (i.e., a different central ring sizeopening or a solid puck) after the original installation, if it isdeemed necessary by the end user to alter the flow dynamics.

Flow Directing Cap Insert Member

Another refractory insert member according to the present invention is aflow directing cap 140 (FIGS. 22A and 22B). As shown, the flow directingcap 140 is a hollow, substantially cylindrical member 140 includes anopen first end 140 a, and opposed second end 140 b (having an opening140 d) and a central cylindrical portion 140 c. The outer diameter ofthe flow directing cap insert is slightly smaller than the innerdiameter of the through-hole 7 of the block to allow for properinsertion but to substantially prevent excess gas flow around theoutside of the insert. The outer peripheral surface of the first end 140a is provided with corresponding mechanical mating features (e.g.,openings/slots 141 a) that by-pass and mechanically engage with the tabs8 on the inner diameter 7 a of the through-hole 7 in the brick (block)100 in the same manner as the tie bar cradle insert 15, 151 describedabove. Specifically, proximate the first end 140 a is an annular flange141 and a parallel annular flange 142 defining a groove or channel 143therebetween. At least the flange 141 includes a pair of diametricallyopposed openings (slots) 141 a that are sized appropriately to allow thetabs 8 to pass therethrough. Preferably, the slots are around about 60°or more (at least slightly bigger than the tabs 8) with respect to thecircumference of the flow directing cap insert 140 and the through-hole7. The space (groove, channel) 143 between the parallel flanges 141 and142 is dimensioned to accept securely retain the tabs 8 therein once theflow directing cap insert member 140 is rotated far enough, preferablyabout 90 degrees.

The second end 140 b of the flow directing cap insert includes anannular lip and the opening 140 d. A hooded, cup-like portion 144 isprovided to obscure or otherwise cover a portion of the opening 140 d soas to direct the gas flow exiting therefrom. The hooded, cup-likeportion can be made to have any opening angle needed, as described, forexample, in connection with U.S. Pat. No. 8,439,102, and/or insertmembers 140 having a single or mixed types of angle-openings can bearranged in through-holes at different locations to control the flow bychanging the orientation of the hood opening/angle.

The refractory block assembly 105 shown in FIG. 22B includes the flowdirecting cap insert member 140 installed in the block 100. Another flowdirecting cap insert 140, or a different type of refractory insertmember, can be inserted in the other through-hole 7 to define a doubleassembly within the same block.

In effect, the flow directing cap insert member 140 enables the flue gasthat passes therethrough to be redirected in a specific direction, otherthan in a direct line with the through-hole of the block, as dictated bythe needs of the end user, and can be placed in any location in thetunnel system that is needed to alter the flow dynamics.

The Tunnel Assembly (Also Referred to Interchangeably Herein as aTunnel)

As shown in FIGS. 25-28, the tunnel assembly 200 includes a plurality ofbase components 30 are arranged to extend horizontally (in a firstdirection or the horizontal arrangement direction, i.e., defining awidth of the tunnel) and are aligned with respect to one another todefine a substantially continuous base surface along the longitudinalextension direction (length) of the tunnel. The base components 30 aresecured to one another via the mechanical mating members 35, 36(preferably without any mortar). A plurality of wall-forming blocks 10are vertically stacked onto the base components 30 on both opposedsides, along the longitudinal extension direction of the tunnel, whichhelps further secure the base components 30 in place. The blocks 10 arearranged in a sequentially off-set manner, by one half of a length onthe base components 30, using the respective mechanical mating members33 (protruding portions from the base components 30) and 4 (openings onthe blocks 10) to securely fasten the blocks 10 into place on the basecomponents 30 without the use of mortar. The blocks 10 are also securedto one another via the respective mechanical mating members 5, 6. Aplurality of blocks 1A, 100 are then stacked vertically and along thelongitudinal extension direction on the row of blocks 10 in a similar,half-block off-set manner.

Additional blocks 1A, 100 are then alternately stacked onto one another,secured to one another vertically and horizontally, preferably withoutmortar, via the respective mechanical mating members 3, 4, 5 and 6,continuing in a half-block, off-set manner, to define two parallel,vertically oriented tunnel walls 8 that extend both in the second (i.e.,vertical arrangement direction) from the base components 30 and in thelongitudinal extension direction of the tunnel. As shown, some of theblocks correspond to the blocks 10 shown in FIG. 11 (withoutthrough-holes 7), and some of the blocks correspond to the blocks 100shown in FIG. 16, which include through-holes 7. Blocks 1A are otherwisethe same as those shown and described as blocks 1 in FIG. 10, with theexception of the though-hole that is included in blocks 1A.

The tunnel walls 8 are spaced a predetermined distance (i.e., 12-60 in,preferably 24 to 36 in) apart from one another in the horizontalarrangement direction, dictated by the horizontal span of the basecomponents 30. Tie bars 50 are inserted into refractory insert members(tie bar cradles 15 or 151) in desired locations, as needed. Otherrefractory insert members, such as refractory plug inserts 130, 136,230, 330, or 430, and flow directing cap insert members 140 can also beinserted into the through-holes 7 of the blocks 100 in the any locationthat is desired to define refractory block assemblies at those points(see, e.g., FIG. 26). The tunnel assembly is secured by placing aplurality of lids 60 across the tops of the tunnel walls 8, which aresecured in place onto the uppermost blocks 10 via the mechanical matingfeatures (e.g., openings 64 in the lids and the protruding portions 3 ofthe wall blocks 10), and further secured to one another via themechanical mating members 65, 66 in the lids 60 to construct the tunnel200 (also referred to as a tunnel assembly 200 or 200A, see, e.g., FIGS.25-29).

As discussed above, in the tunnel 200 according to the presentinvention, reducing the weight of all of the components, whilemaintaining the structural integrity of each of the individualcomponents, makes it possible to eliminate much of the crushing force onthe lower courses of the brick (i.e., the base components 30). Providinglight-weight, structurally correct cover (lid) components 60 overcomesthe drawbacks previously associated with making conventional lidsthicker in order to be stronger, which also detrimentally addedadditional load to the entire system. The incorporation of controlledexpansion gaps between each brick and elimination of mortar from theoverall system ensures that the tunnel assembly 200 can expand andcontract without creating large cumulative stresses, and reduces theinstallation time of the tunnel assembly 200, 200A as a whole.

With the reduced wall thickness and improved materials used for thecomponents, the light-weight tunnel lids 60 can be easily installed orremoved simply by two laborers. In addition, the light-weight,mortar-free blocks with interlocking mechanical mating features areeasily handled by a single laborer, and the tunnel structure 200 canassembled, repaired and/or disassembled as necessary without significantconsequences or the requirement for high levels of skill. Cross beamsupports (i.e., tie bars 50 in respective cradle inserts), as well asother refractory insert members, such as flow restricting/constrictingplugs and flow directing caps, can be easily added or removed from theblocks (block assemblies) in the tunnel assembly 200 without limitingaccess to other tunnel components during turnarounds, ensuring thatrepairs can be complete and effective. Faster installation and repairtime also allows for proper repairs to be made more readily, improvingthe overall reliability of the system.

FIGS. 26 and 27 best illustrate an example of a tunnel 200 including acombination of different blocks 1A, 10 and 100 and defining a number ofdifferent refractory assemblies (e.g., 104, 104′, 104″ and 102).Although this embodiment does not depict a flow directing cap insertmember, any of the various refractory inserts according to the presentinvention can be used in conjunction with any through-hole location inany of the blocks of the tunnel system to define a refractory blockassembly within the tunnel assembly, thereby providing a modular systemthat allows for a universal refractory insert-mating tab to be providedon the surface of the openings of the blocks that are be used inconjunction with any insert in any location in the tunnel. This vastflexibility enables the end user to modify the installation ofrefractory insert members in any manner that they deem necessarydepending on the particular processing conditions and requirements thatthey face.

While the present invention has been shown and described above withreference to specific examples, it should be understood by those skilledin the art that the present invention is in no way limited to theseexamples, and that variations and modifications can readily be madethereto without departing from the scope and spirit of the presentinvention.

What is claimed is:
 1. A refractory block assembly comprising: anrefractory block having at least one opening formed therein; and atleast one refractory insert member that resides within the at least oneopening in the refractory block.
 2. The refractory block assemblyaccording to claim 1, wherein said at least one refractory insert membercomprises mechanical mating member that engages a correspondingmechanical mating member provided on an inner surface of the at leastone opening in the refractory block.
 3. The refractory block assemblyaccording to claim 2, wherein the mechanical mating member of therefractory insert member comprises a slot and groove that mechanicallyengage and retain a corresponding tab provided on the inner surface ofthe at least one opening of the refractory block.
 4. The refractoryassembly according to claim 1, wherein the at least one refractoryinsert member is at least at least one of a gas flow changing plug, agas flow restricting puck, a gas flow changing cap, and a tie barcradle.
 5. A refractory block assembly for a steam reformer furnacetunnel, the refractory block assembly comprising: a hollow main bodyportion having an outer peripheral surface defining a first end, anopposed second end, an upper surface, an opposed lower surface, a firstside and an opposed second side; at least one through-hole havingopenings formed in the first side and the opposed second side of themain body portion; a refractory insert member that resides within atleast one of the at least one though-hole, the refractory insert membercomprising a mechanical mating member that engages a correspondingmechanical mating member provided on an inner surface of the at leastone through-hole; at least one first mechanical mating portion defininga protruded portion extending from a portion of the upper surface of themain body portion; and at least one second corresponding mechanicalmating portion defining an opening corresponding to the protrudedportion formed in a portion of the lower surface the main body portion.6. The refractory block assembly according to claim 5, wherein themechanical mating member of the refractory insert member comprises aslot and groove that mechanically engage and retain a corresponding tabprovided on the inner surface of the at least one through-hole.
 7. Therefractory block assembly according to claim 5, wherein the at least onerefractory insert member is at least one of a gas flow changing plug, agas flow restricting puck, a gas flow changing cap, and a tie barcradle.
 8. A refractory insert member comprising: a main body parthaving a first end, an opposed second end, and an outer peripheralsurface; and a mechanical mating member provided on at least a portionof the outer peripheral surface thereof.
 9. The refractory insert memberaccording to claim 8, wherein the mechanical mating member comprises atleast one slot.
 10. The refractory insert member according to claim 9,wherein the mechanical mating member comprises at least twodiametrically opposed slots.
 11. The refractory insert member accordingto claim 8, wherein the mechanical mating member comprises at least oneflange having at least one slot and a channel, open to the slot,extending around at least a portion of the outer peripheral surface ofthe main body.
 12. The refractory insert member according to claim 11,wherein the mechanical mating member comprises at least one flangehaving two diametrically opposed slots and a channel, open to the slots,extending around the outer peripheral surface of the main body betweenthe slots.
 13. The refractory insert member according to claim 11,wherein the mechanical mating member comprises two parallel flangesseparated from one another by the channel located between the flanges,wherein at least one of the flanges has two diametrically opposed slotsopen to the channel, and wherein the channel extends around at least aportion of the outer peripheral surface of the main body between theslots.
 14. The refractory insert member according to claim 8, whereinthe refractory insert member is at least one of a gas flow changingplug, a gas flow restricting puck, a gas flow changing cap, and a tiebar cradle.
 15. A refractory tunnel assembly for a steam reformerfurnace, the tunnel assembly comprising: a plurality of hollow basecomponents, each the base component comprising a plurality ofcorresponding mechanical mating members; a plurality of hollow wallblocks, each the wall block comprising a plurality of correspondingmechanical mating members that further correspond to the mechanicalmating members of the base components, wherein at least a portion of theplurality of wall blocks further comprise at least one through-holehaving openings formed in opposed side surfaces thereof; a plurality ofhollow lid components, each said lid component comprising a plurality ofmechanical mating members that further correspond to said mechanicalmating members of said base components and said wall blocks; and one ormore refractory insert members that reside within one or more of thethough-holes in said wall blocks; wherein said base components arearranged to extend in a horizontal arrangement direction defining awidth of the tunnel assembly and a longitudinal arrangement directiondefining a length of the tunnel assembly; wherein the wall blocks arestacked upon and mechanically interconnected to the base components viathe corresponding mechanical mating members in a vertical arrangementdirection and along the longitudinal arrangement direction, and arestacked upon one and mechanically interconnected to another via thecorresponding mechanical mating members, without the use of mortar, inboth the vertical and longitudinal arrangement directions, to define twoparallel tunnel walls, spaced a distance apart from one another in thehorizontal arrangement direction, wherein the tunnel walls extendupwardly from the base components in the vertical arrangement directionand along the length of the tunnel assembly on the base components; andwherein the plurality of lid components are stacked upon andmechanically interconnected to the wall blocks via the mechanical matingmembers, without the use of mortar, in the vertical arrangementdirection and along the longitudinal arrangement direction, so that thelids extend along the longitudinal arrangement direction and thehorizontal arrangement direction in order to cover the distance betweenthe tunnel walls along at least a portion of the length of the tunnelassembly.
 16. The refractory tunnel assembly according to claim 15,wherein the base components, the wall blocks, the lid components, andthe refractory insert members all comprise the same material.
 17. Therefractory tunnel assembly according to claim 15, further comprising atleast one tie bar extending between the tunnel walls in the horizontalextension direction and having a first end located in a portion of afirst refractory insert member and a second end located in a portion ofan opposed second refractory insert member.
 18. The refractory tunnelassembly according to claim 15, wherein the at least one refractoryinsert member comprises a mechanical mating member that engages acorresponding mechanical mating member provided on an inner surface ofthe at least one through-hole of the wall blocks.
 19. The refractoryblock according to claim 18, wherein the mechanical mating member of therefractory insert member comprises a slot and channel that mechanicallyengage a corresponding tab provided on the inner surface of the at leastone through-hole of the wall blocks.
 20. The refractory assemblyaccording to claim 15, wherein the at least one refractory insert memberis at least one of a gas flow changing plug, a gas flow restrictingpuck, a gas flow changing cap, and a tie bar cradle.